@mesh-tech/mesh-cli/assets/log-shipper.mjs

CLI for Mesh platform development utilities

#!/usr/bin/env node
/**
 * mesh dev --local log shipper.
 *
 * Sits at the end of each service's launch pipeline:
 *   { <dev command>; } 2>&1 | node log-shipper.mjs
 *
 * - Echoes every byte to stderr untouched (the tmux pane keeps colors).
 * - Ships ANSI-stripped lines to the local platform's OTel collector via
 *   OTLP/HTTP — the SAME ingestion path instrumented apps use, carrying the
 *   resource attributes `mesh dev` injects (OTEL_RESOURCE_ATTRIBUTES /
 *   OTEL_SERVICE_NAME), so Loki indexes k8s_namespace_name /
 *   k8s_deployment_name exactly like the in-cluster k8sattributes processor.
 *
 * Why not a log file tailed by the collector: host-written files cross the
 * macOS Docker mount with stale attributes — appends can stay invisible to
 * the in-container tailer indefinitely. OTLP over localhost has no such
 * boundary. Shipping is best-effort: the collector being down never breaks
 * the dev loop.
 */

const ENDPOINT = (process.env.OTEL_EXPORTER_OTLP_ENDPOINT ?? "http://localhost:4318").replace(/\/+$/, "");
const FLUSH_MS = 1000;
const MAX_BATCH = 200;

const attributes = [];
for (const pair of (process.env.OTEL_RESOURCE_ATTRIBUTES ?? "").split(",")) {
  const eq = pair.indexOf("=");
  if (eq > 0) {
    attributes.push({ key: pair.slice(0, eq).trim(), value: { stringValue: pair.slice(eq + 1).trim() } });
  }
}
if (process.env.OTEL_SERVICE_NAME) {
  attributes.push({ key: "service.name", value: { stringValue: process.env.OTEL_SERVICE_NAME } });
}

const ANSI = /\x1b\[[0-9;?]*[ -/]*[@-~]|\x1b\][^\x07\x1b]*(?:\x07|\x1b\\)?|\x1b[=>]|\r/g;

let queue = [];
let flushTimer = null;
let flushing = Promise.resolve();

function enqueue(line) {
  const clean = line.replace(ANSI, "");
  if (!clean.trim()) return;
  queue.push({ timeUnixNano: String(Date.now()) + "000000", body: { stringValue: clean } });
  if (queue.length >= MAX_BATCH) flush();
  else if (!flushTimer) flushTimer = setTimeout(flush, FLUSH_MS);
}

function flush() {
  if (flushTimer) {
    clearTimeout(flushTimer);
    flushTimer = null;
  }
  if (queue.length === 0) return flushing;
  const logRecords = queue;
  queue = [];
  const payload = JSON.stringify({
    resourceLogs: [
      {
        resource: { attributes },
        scopeLogs: [{ scope: { name: "mesh-dev-local" }, logRecords }],
      },
    ],
  });
  flushing = fetch(`${ENDPOINT}/v1/logs`, {
    method: "POST",
    headers: { "content-type": "application/json" },
    body: payload,
    signal: AbortSignal.timeout(5000),
  }).catch(() => {
    /* best-effort — never break the dev loop */
  });
  return flushing;
}

let buffer = "";
process.stdin.on("data", (chunk) => {
  process.stderr.write(chunk); // raw passthrough → the tmux pane
  buffer += chunk.toString("utf-8");
  let newline;
  while ((newline = buffer.indexOf("\n")) >= 0) {
    enqueue(buffer.slice(0, newline));
    buffer = buffer.slice(newline + 1);
  }
});

process.stdin.on("end", async () => {
  if (buffer) enqueue(buffer);
  await flush();
  await flushing;
  process.exit(0);
});